Airborne geophysical surveys in central West Greenland and central East Greenland in 1997

Author(s):  
Leif Thorning ◽  
Robert W. Stemp

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Thorning, L., & Stemp, R. W. (1998). Airborne geophysical surveys in central West Greenland and central East Greenland in 1997. Geology of Greenland Survey Bulletin, 180, 63-66. https://doi.org/10.34194/ggub.v180.5087 _______________ In order to stimulate mining exploration activity in Greenland the Government of Greenland decided in 1993 to finance a five-year programme of airborne electromagnetic surveys over selected regions of Greenland, Project AEM Greenland 1994–1998. By the end of 1996 three surveys had been undertaken in various parts of Greenland (Stemp & Thorning 1995a, b; Stemp 1996a, b; Stemp 1997a, b). In 1992 the Danish Government financed a small aeromagnetic survey (Project Aeromag 1992; Thorning 1993). Regional aeromagnetic surveying was taken up again when the governments of Denmark and Greenland jointly financed two aeromagnetic surveys in 1995 and 1996 – the projects Aeromag 1995 and Aeromag 1996 (Thorning & Stemp 1997). To this suite of airborne geophysical surveys of selected regions in Greenland were added two surveys in 1997, both financed by the Government of Greenland. The fourth year of Project AEM Greenland 1994–1998 encompassed a transient electromagnetic (GEOTEM) and magnetic survey over northern Jameson Land, central East Greenland, while Project Aeromag 97 added a regional aeromagnetic survey over Disko Bugt – Nuussuaq, central West Greenland. As in previous years, commercial geophysical contractors carried out the survey operations in Greenland according to an agreement with the Geological Survey of Denmark and Greenland (GEUS) entered into after international tendering following rules of the European Union. GEUS manages the projects and organises the distribution and use of the results. The new maps and digital data from the two 1997 surveys, a total of 85 252 line kilometres of data covering 51 414 km2, were released to the public on 1 March 1998. This note provides some introductory information about the two surveys. Further information can be found in reports by Stemp (1998) and Thorning (in press); both include a number of full-page colour anomaly maps from the survey areas. The airborne geophysical programme will continue in 1998, and the areas to be surveyed have already been selected. The final year of Project AEM Greenland 1994–1998 will include combined GEOTEM and magnetic surveys over two regions in North Greenland: Washington Land in western North Greenland, where operations are expected to start in May 1998 operating out of Alert in Canada, and later in the season over J.C. Christensen Land in central North Greenland operating out of Station Nord in eastern North Greenland. Project Aeromag 1998 will continue the regional aeromagnetic survey programme in West Greenland, extending the coverage by including most of the region from 63°45′N to 66°N in southern West Greenland. This project will be based at Nuuk and start in March 1998. The Government of Greenland will finance all surveys in 1998. Figure 1 shows all survey areas for the electromagnetic and magnetic surveys of Project AEM Greenland 1994–1998 and the aeromagnetic survey areas of Project Aeromag 1992, 1995, 1996, 1997 and 1998.

Author(s):  
Robert W. Stemp

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemp, R. W. (1997). Airborne geophysical surveys in Greenland – 1996 update. Geology of Greenland Survey Bulletin, 176, 75-79. https://doi.org/10.34194/ggub.v176.5069 _______________ Two major airborne geophysical surveys were carried out in 1996, the third year of a planned five-year electromagnetic and magnetic survey programme (project AEM Greenland 1994–1998) financed by the Government of Greenland, and the second year of an aeromagnetic survey programme (project Aeromag) jointly financed by the governments of Denmark and Greenland; both projects are managed by the Geological Survey of Denmark and Greenland (GEUS). The two 1996 surveys were: 1) Project Aeromag 1996 in South-West and southern West Greenland;2) Project AEM Greenland 1996 in South-West Greenland. All areas surveyed and planned for future surveys as of March 1997 are shown in Figure 1. Results of both the 1996 surveys were released in March 1997, as a continuation of a major effort to make high quality airborne geophysical data available for both mineral exploration and geological mapping purposes. The data acquired are included in geoscientific databases at GEUS for public use; digital data and maps may be purchased from the Survey. The main results from the 1996 surveys are described in Thorning & Stemp (1997) and Stemp (1997). Two further new airborne surveys have already been approved for data acquisition during the 1997 field season, with subsequent data release in March 1998. A summary of all surveys completed, in progress or planned since the formal inception of project AEM Greenland 1994–1998 is given in Table 1. The programme was expanded to include a separate regional aeromagnetic survey in 1995, provisionally for 1995–1996, with extension subject to annual confirmation and funding.


Author(s):  
Thorkild M. Rasmussen ◽  
Leif Thorning

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & Thorning, L. (1999). Airborne geophysical surveys in Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 34-38. https://doi.org/10.34194/ggub.v183.5202 _______________ Airborne geophysical surveying in Greenland during 1998 consisted of a magnetic project referred to as ‘Aeromag 1998’ and a combined electromagnetic and magnetic project referred to as ‘AEM Greenland 1998’. The Government of Greenland financed both with administration managed by the Geological Survey of Denmark and Greenland (GEUS). With the completion of the two projects, approximately 305 000 line km of regional high-resolution magnetic data and approximately 75 000 line km of detailed multiparameter data (electromagnetic, magnetic and partly radiometric) are now available from government financed projects. Figure 1 shows the location of the surveyed areas with highresolution geophysical data together with the area selected for a magnetic survey in 1999. Completion of the two projects was marked by the release of data on 1 March, 1999. The data are included in the geoscientific databases at the Survey for public use; digital data and maps may be purchased from the Survey.


Author(s):  
Thorkild M. Rasmussen ◽  
Jeroen A.M. Van Gool

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & van Gool, J. A. (2000). Aeromagnetic survey in southern West Greenland: project Aeromag 1999. Geology of Greenland Survey Bulletin, 186, 73-77. https://doi.org/10.34194/ggub.v186.5218 _______________ The acquisition of public airborne geophysical data from Greenland that commenced in 1992 continued in 1999 with project Aeromag 1999, an aeromagnetic survey of part of southern West Greenland. This paper presents results of the aeromagnetic survey and discusses the correlation of the measured data with the previously mapped surface geology. The project was financed by the Government of Greenland and managed by the Geological Survey of Denmark and Greenland. Sander Geophysics Ltd., Ottawa, Canada, was selected in April 1999 as the contractor for the project through a European Union opentender procedure.


Author(s):  
Thorkild M. Rasmussen

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article. Rasmussen, T. M. (1). Aeromagnetic survey in central West Greenland: project Aeromag 2001. Geology of Greenland Survey Bulletin, 191, 67-72. https://doi.org/10.34194/ggub.v191.5130 The series of government-funded geophysical surveys in Greenland was continued during the spring and summer of 2001 with a regional aeromagnetic survey north of Uummannaq, project Aeromag 2001 (Fig. 1). The survey added about 70 000 line kilometres of high-quality magnetic measurements to the existing database of modern airborne geophysical data from Greenland. This database includes both regional high-resolution aeromagnetic surveys and detailed surveys with combined electromagnetic and magnetic airborne measurements.


1972 ◽  
Vol 41 ◽  
pp. 1-39
Author(s):  
A Weidick

Post-Wisconsinian uplift of West, North and East Greenland has been estimated on the basis of information in current literature and compared to the data collected by the author in central West Greenland. For West and North Greenland the dated uplift allows an estimate to be made of the age of former shore-lines, which in turn have been used to date the stages of the extent of the Inland lce. The results have been compared with published information on the age of glacial stages in East Greenland. The estimated ages of the ice margin stages imply a history of deglaciation in West (and North?) Greenland comparable to that of North America. In both areas the major deglaciation took place after the Younger Dryas and a marked halt took place in Boreal times. It is possibie that the history of East Greenland is more closely related to that of Scandinavia where a widespread deglaciation took place prior to the Younger Dryas. The deglaciation of North Greenland was interrupted by a marked readvance or readvances during the climatic optimum. It is possible that the northward shift of the low pressure centres during this period led to an increased accumulation on the northern part of the Inland lce.


Author(s):  
Ole Bennike

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Bennike, O. (1998). Pingos at Nioghalvfjerdsfjorden, eastern North Greenland. Geology of Greenland Survey Bulletin, 180, 159-162. https://doi.org/10.34194/ggub.v180.5101 _______________ Pingos are isolated, conical mounds up to 50 m high with a core of ice covered by silt, sand or gravel. They are formed in regions where the ground is permanently frozen. Two types of pingo are distinguished, a closed-system and an open-system (Washburn 1979; Pissart 1988). The closed-system type is found on flat plains, whereas open-system pingos are found on valley floors. Open-system pingos grow by artesian pressure (Müller 1959; Washburn 1979). Water from higher altitudes migrates within or below the permanently frozen ground and becomes trapped within the permafrost and freezes to form a lens or core of ice. Active pingos have been reported from Svalbard, Russia, Alaska, Canada and Greenland (Washburn 1979), and fossil pingos from Pleistocene periglacial terrains have been reported from Europe and North America (De Gans 1988). In Greenland, most pingos have been reported from both East and West Greenland. In East Greenland pingos have been described from the area between 71°30′ and 74°30′N (Fig. 1). In West Greenland most pingos occur between 70° and 72°N. In addition, a pingo and some pingo-like forms have been described from North Greenland (Bennike 1983). All pingos in Greenland are located in valleys, usually on outwash plains. During field work in 1997 one fairly impressive pingo and several small pingos or pingo-like forms were observed at c. 79°30′N in eastern North Greenland. These are the northernmost pingos recorded from eastern Greenland, and the aim of this note is to document and describe these forms. The observations add to our knowledge about the distribution of pingos in Greenland, and a map showing the distribution of pingos in Greenland is presented as Fig. 1.


1994 ◽  
Vol 160 ◽  
pp. 47-51
Author(s):  
N Henriksen

The Geological Survey of Greenland (GGU) initiated in 1964 a 1:500000 mapping programme to produce a general overview of the onshore geology of all the ice-free areas of Greenland. So far 10 of a total of 14 planned map sheets have been published, and one additional sheet for which field work has been completed is under compilation. Most of Greenland is therefore now covered by map sheets of this series and only three areas remain to be covered: in North-West Greenland (sheet 6), in eastern North Greenland (sheet 9) and in East Greenland (sheet 11). Eastern North Greenland (map sheet no. 9; Fig. 1) is the target of the present project, with planned field work from 1993–1995. The first season (1993) was used for logistical preparation and geological reconnaissance in advance of the more intensive field work in the two following seasons (1994–95).


1996 ◽  
Vol 172 ◽  
pp. 71-73
Author(s):  
L Thorning ◽  
R.W Stemp

Two major airborne geophysical surveys were carried out during 1995. The second year of a planned five-year electromagnetic and magnetic survey programme (project AEM GreenJand 1994-1998) financed by lhe Government of Greenland, and the first year of an aeromagnetic survey programme (project AEROMAG 1995-1996) jointly financed by lhe governmems of Denmark and Greenland; both projecls are managed by the Geological Survey of Denmark and Grcenland (GEUS).


Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1044
Author(s):  
Jianfei Fu ◽  
Sanshi Jia ◽  
Ende Wang

The detection and evaluation of concealed mineral resources deep in metallic mines and in the surrounding areas remain technically difficult. In particular, due to the complex topographic and geomorphic conditions on the surface, the detection environments in these areas limit the choices of detection equipment and data collection devices. In this study, based on metallogenic theory and the metallogenic geological characteristics of banded iron formation (BIF)-type iron ores, equipment for surface geophysical surveys (i.e., the high-precision ground magnetic survey method, the transient electromagnetic method, and the magnetotelluric method) and data collection devices capable of taking single-point continuous measurements were employed to detect the concealed iron ore bodies in the transition zone CID-1 between the Hejia and Dumu iron deposits in the Gongchangling iron ore concentration area in the Anshan-Benxi area (Liaoyang, China), a representative area of BIF-type iron ores. The results showed that an optimal combination of these geophysical survey methods accurately determined the anomalous planar spatial locations and anomalous profile morphologies of the concealed iron ore bodies. On this basis, we determined their locations, burial depths, and scales. Two anomalous zones induced by concealed iron ore bodies, YC-1 and YC-2, were discovered in zone CID-1. Two concealed iron-bearing zones, one shallow (0–150 m) and one deep (300–450 m), were found in YC-1. A 100 m scale drilling test showed that the cumulative thickness of the shallow iron-bearing zone was over 23.6 m.


Author(s):  
Kai Sørensen

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, e.g.: Sørensen, K. (2002). The year in focus, 2001. Geology of Greenland Survey Bulletin, 191, 9-12. https://doi.org/10.34194/ggub.v191.5057 Field activities in Greenland by the Geological Survey of Denmark and Greenland (GEUS) in 2001 were again many and varied. They included economic investigations of crystalline basement and sedimentary rocks in North-West Greenland, and a systematic mapping project combined with resource evaluation in the boundary zone of the Nagssugtoqidian and Rinkian mobile belts of central and southern West Greenland. In addition, studies of the Vendian to Lower Palaeozoic successions in North-East Greenland and of the Palaeogene sediments of central East Greenland were carried out, a major aeromagnetic survey was flown in central West Greenland, and investigations of Holocene lake sediments in southern West Greenland were continued.


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